There are known several glutathione-S-lower fatty acid derivatives. Among them, S-(2-carboxypropyl)glutathione has been isolated from onion and garlic (Virtanen and Matikkala, Hoppe-Seylers Z. Physiol. Chem., Bd 322, pages 8-20, 1960; Suzuki et al., Chem. Pharm. Bull., Vol. 9, pages 77-78, 1961) but there is little information on its pharmacologic activity.
The inventors of the present invention previously found that glutathione-S-succinic acid derivatives have platelet aggregation-inhibitory, antiinflammatory, antiallergic, antitumoral and hepatic impairment-protective activities (Japanese Kokai Patent Application No. 63-8337 and Japanese Patent Application No. 1-79956, No. 1-183484, No. 1-256370 and No. 2-36745).
In search of still more pharmacologically active compounds, the inventors of the present invention synthesized a variety of novel glutathione derivatives and screened them, as well as said S-(2-carboxypropyl)glutathione, for their pharmacologic activities. As a consequence, they found that S-(2-carboxypropyl)glutathione and a series of compounds which can be synthesized by reacting glutathione or an ester thereof with an .alpha., .beta.-unsaturated fatty acid, such as acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, etc., or an .alpha. (or .beta.)-halogenated organic monocarboxylic acid, such as monochloroacetic acid, or an ester or amide thereof have excellent antihepatopathic efficacy. The present invention has been attained based on this finding.